Fluid container and capsule therefor

ABSTRACT

A fluid container and capsule therefor. The capsule comprises upper and lower parts, at least one of which has a dished formation and both of which have a peripheral rim, the rims being secured together so that the upper and lower parts are at least partially in register with one another to provide at least one vented chamber extending into the dished formation. The capsule includes a vent hole or like structure in at least one of the parts to communicate between the interior of the chamber and the exterior thereof. The lower part has its exterior so formed as to enable it to be held in stable engagement with a surface but so that a fluid may pass freely between those parts of the exterior of the lower part and the surface that are not in intimate engagement.

This invention relates to a capsule for storing and dispensing at leastone fluid under pressure and also to a metal fluid container for storingand dispensing fluids, generally liquids, under pressure and whichincorporates such a capsule. The invention is particularly although notexclusively concerned with containers for carbonated beverages. Suchcontainers may be of steel or of an aluminium alloy or of aplastics/metal laminate or of plastics material.

It is well known with some beers, and particularly draught stout for itto be desirable that a creamy head should be formed on the beer when itis poured. Many such beers are now sold in cans, usually of an aluminiumalloy and are pressurised by a gas. When the can is opened someformation of a head will occur but it is well known to enhance this byproviding a second chamber in the form of a capsule within the can, thecapsule communicating with the interior of the can via a valve or one ormore small holes.

Frequently such capsules are of plastics material and are a friction fitwithin the can. Specifications GB 2183592 and GB/PCT 91/07326 show sucharrangements. However friction fit capsules may damage the thinprotective coating customarily applied to the interior of the cans.

Other arrangements have also been proposed in which at least part of thecapsule is formed as a part of the can construction either at the top orbottom thereof.

The recycling of cans of aluminium alloy is now widely practised and ithas been found that when they contain capsules of plastics materialproblems arise in the furnaces used.

When the can is used for draught stout the second chamber constituted bythe capsule is subject to various pressures in the following ways:

1) It is subject to atmospheric pressure when it is installed in the canand subsequently when the stout is first poured in.

2) When the can is sealed the pressure therein quickly rises to about 40psi. The pressure within the capsule rises more slowly because the fluidenters the capsule more slowly. At this stage the overall pressure onthe capsule acts in the sense to collapse it.

3) Pasteurisation of the can at, say, 60°-80° C. causes the pressuretherein to rise to say 70-80 psi. The pressure in the capsule will againlag behind that in the body of the can and the degree of lag will dependboth upon the size of the hole or holes in the capsule (or the nature ofits valve) and the rate of heating. Again the overall pressure on thecapsule acts in the sense to collapse it. On cooling after thepasteurisation process the pressure within the can and the capsulereverts to an equilibrium position at about 40 psi.

4) When the can is opened its internal pressure drops to atmosphericsubstantially instantly while the pressure within the capsule initiallyremains at about 40 psi. This pressure difference causes the stout plusgas within the capsule to be ejected forcefully through the hole orholes or through a valve in the capsule to generate the desired head.Thus when the can is first opened and for a short time thereafter theoverall pressure on the capsule acts in the sense to inflate it.

Thus the capsule must be able to resist pressures which tend both tocollapse and inflate it.

For the purpose set out above when the container is for a carbonatedbeverage it may be of an aluminium alloy or of steel and the capsuleshould in such case also be metallic, for example of an aluminium alloy.However it is also envisaged that the container including a capsule mayhave other uses for example in the food industry for providing two partformulations under pressure. Other uses including the storage anddispensing of adhesives are also envisaged.

Accordingly for different uses a container may be of steel, or analuminium alloy or a plastics/metal laminate or a plastics material andthe capsule may be wholly or partly of plastics or metal.

According to one aspect of the present invention there is provided acapsule comprising upper and lower parts at least one of which has adished formation and both of which have a peripheral rim, the rims beingsecured together so that the formations are at least partially inregister with one another to provide at least one vented chamberextending into the dished formation of said dished part, means in atleast one of the parts to communicate between the interior of thechamber and the exterior thereof and the lower part having its exteriorso formed as to enable it to be held in stable engagement with a surfacebut so that a fluid may pass freely between those parts of the exteriorof the lower part and the surface that are not in intimate engagement.

The present invention also provides a fluid container having a generallycylindrical body and comprising a top a base and an annular side wall atleast part of the body defining a closed primary chamber openable bymanually operable means in the top the base projecting inwardly of thechamber to present an inner surface a capsule being disposed within thecontainer and held in stable engagement against the surface.

Another aspect of the present invention is a metallic fluid containerhaving a generally cylindrical body and comprising a top, a base and anannular side wall at least part of the body defining a closed primarychamber openable by manually operable means in the top; a capsuleproviding a secondary chamber within the body which is closed except formeans therein to provide selective communication between the chambersthe means being located at a position within the container so that whenthe fluid is a liquid and the container is in an upright position saidmeans is always within the body of such liquid the capsule having wallsof an aluminium alloy of a thickness less than 500 microns at least oneof which is bonded to the base or the side wall.

The invention also provides a fluid container having a generallycylindrical body and comprising a top a base and an annular side wall atleast part of the body defining a closed primary chamber openable bymanually operable means in the top, the base projecting inwardly of thechamber to present an inner surface a member having a dished formationand a rim secured to the inner surface so that the member and the partof the inner surface inwardly of the rim constitute a capsule and meansin the member to communicate between the interior of the chamber and theexterior thereof.

Various embodiments of the invention will now be described by way ofexample with reference to the accompanying drawings in which:

FIG. 1 is a vertical section through a capsule,

FIG. 2 is a plan view of the capsule of FIG. 1,

FIG. 3 shows, in section the lower end of a metal fluid containerincorporating a different capsule,

FIGS. 4 to 6 show, diagrammatically, modifications of the arrangement ofFIG. 1,

FIG. 7 shows an edge view of a flange indent,

FIG. 8 shows the use of a plastic rivet,

FIG. 9 shows a modified flange arrangement,

FIG. 10 shows an alternative to FIG. 3,

FIG. 11 shows another arrangement.

FIGS. 12 and 13 show parts of the capsule of FIG. 1 showing ways ofproviding a hole between the flanges and

FIG. 14 is a view in the direction of the arrow `A` in FIG. 13 and afterremoval of the mandrel.

Referring to FIGS. 1 and 2 a capsule indicated generally at 100 hasupper and lower parts 101 and 102 which are either moulded from aplastics material; press-formed of aluminium alloy foil or comprise oneplastics and one foil part. The parts 101 and 102 each have an outerflange 103, 104, an annular dished formation 105, 106 and generally flatregions 107, 108 lying within the formations 105 and 106. These regionslie in the same planes as the respective flanges 103 and 104. Thus thedished formations 105, 106 together form a toroidal chamber 100a. Threeradial recesses 109 are formed in the dished formations 105 and 106;these are significant only in respect of one of the parts as will bedescribed later but it is convenient both from a manufacturing and anorientation point of view to form them in both parts.

The outer edges 110, 111 of the flanges 103, 104 are curled inwardly fora purpose to be described later and the parts are secured together byadhesive (such bonding including heat sealing of plastics material andplastics coated material) bonding around their flanges and flat regions.When both parts are of aluminium foil a vent hole (not shown) will beformed between the flanges as will be described later and when one orboth parts are of plastics material such vent hole may be formed at anyconvenient location. The vent hole may be parallel sided, tapered orstepped and its smallest diameter may be as low as 100 μm. When one orboth of the parts 101, 102 is of plastics material this is preferably offood grade polypropylene having a thickness of 0.5 to 1.5 mm andpreferably about 0.8 mm. For carbonated drinks any vent hole in theplastics material should be 200 to 500 μm in diameter (at its smallest)and may be parallel sided or tapered. For other uses and for substancesother than liquids and gases (for example slurries) the vent hole orholes could be of greater diameter.

If a multiplicity of holes is used it will be understood that they mayeach have a diameter smaller than if only one hole is provided.

The parts may be formed by conventional injection moulding techniques;they may be similar or dissimilar and they may provide, when joined,more than one sealed chamber. Also, in the case of capsules with atleast one plastic part this may be fitted with a valve of known forminstead of being provided with a vent hole. Such an arrangement enablesthe capsule to be filled with a fluid or other flowable substance inadvance of incorporation in a storage container.

Although food grade polypropylene is one useful plastics material, glassreinforced plastics or carbon fibre reinforced material may also beused.

When the capsule 1 is to be incorporated in a carbonated beverage can(as shown for example in FIGS. 3, 10 and 11) which is deep drawn from analuminium alloy it is commonplace to have an inwardly curved bottom wall5 providing a convex inner surface. It is convenient to be able tolocate the capsule of FIGS. 1 and 2 on such a surface and to this endthe outer surface of 105, 106 will fit, in a stable manner on thesurface. The recesses 109 ensure that fluid may flow freely between thecapsule and the surface.

This free flow of fluid may be enhanced by providing, instead of therecesses 109, three outwardly projecting ribs (not shown) on the outersurface of the recess 106 of the lower part 102.

When one of the parts is of aluminium foil the capsule could be securedto the surface by ultrasonic welding but when the capsule is wholly ofplastics material it is preferable to secure it to the surface byadhesive bonding. Alternatively whatever the material of the capsule itcould be held against the surface by mechanical means (not shown).

However the preferred method of securing the capsule in a container isby adhesive bonding. When the container has an epoxy lining, which islikely for carbonated beverage containers the adhesive used may be anethylene vinyl acetate co-polymer plus resin (i.e. an EVA contactadhesive). Alternatively a hot melt adhesive (such as an EVA adhesive)may be used.

Referring now to FIG. 3 as mentioned above, the lower end of a deepdrawn aluminium alloy can 1 is of circular cross-sectional shape and hasa side wall 2 and a shaped bottom wall 3 to provide an annular ridgedpart 4 and an inwardly curved bottom wall 5 having a convex innersurface. It will be understood that the upper end of the can (not shown)is provided with a top wall incorporating a ring-pull.

The ridged part 4 is inset from the periphery of the can to enable it tostack on another can and this part also enables the can to stand on aflat surface. The can thus far described is well known and is producedin large numbers as beverage containers. It will be understood that thecan may be of steel.

A capsule 6 comprising a second chamber is disposed internally at thelower end of the can. This capsule is press-formed of aluminium alloyfoil components and comprises (in the arrangement of FIG. 3) identicalpressed-out parts 7 and 8 having rolled edges 9 and 10 which are bondedtogether to provide the capsule having an annular side wall 11 andinwardly dished top and bottom walls 12 and 13. It will be understoodthat bonding can be adhesive bonding, heat sealing or ultrasonicwelding. The walls 12 and 13 are curved so that they meet at theircentre --A-- and, moreover their curvature is such that the bottom wall13 sits snugly on the bottom wall 5 of the can.

The capsule 6 may be circular in cross-sectional shape; it may be ovalor, for example it may be generally rectangular, with rounded corners.The parts 7 and 8 are preferably formed from an alloy selected from1xxx, 3xxx, 5xxx or 6xxx series; preferably 3xxx, and be chosen to becompatible with the can-stock alloy used, say 3004, or a magnesium freealloy such as 3003 so that recycling of the can including the secondchamber presents no problems.

The parts 7 and 8 are preferably of foil or thin sheet having athickness of 40 to 500 μm. When the parts are of foil they may be from50 to 300 μm with 100 to 200 μm being the preferred range. The externalsurfaces of the parts 7 and 8 are coated with a stoving lacquer that isof sterilisable grade and has a thickness of 2 to 20 μm, preferably 3 to5 μm. Internally, or if desired also externally, the parts 7 and 8 havea polypropylene/lacquer laminated to or coated on the foil before theparts are pressed out. This lamination may have a thickness of 20 to 75μm and is preferably about 50 μm. The grade of polypropylene used shouldsoften at not less than 85° C. and melt at about 160° C. Contact timeshould be 0.1 to 5 secs and typically 0.5 secs and it should be of foodgrade quality.

The capsule 6 may be secured to the can by a single bond at the positionA or by means of ultrasonic welding when the external surface of thepart 7 has an appropriate laminated coating. Alternatively all or partof the mating surfaces could be provided with a patch of adhesive at theposition A and localised heat applied thereto. In both cases theappropriate tool (not shown) can extend through the can before the topwall is secured thereto or tools may be applied to the inside and/or theoutside of the can.

It will be understood that the interior of the capsule 6 must be ventedto the interior of the can. This may be achieved in a number ofdifferent ways as will be described later.

Although the parts 7 and 8 have been described and shown as identical itwill be understood that they may differ. For example the curvature ofthe top and bottom walls 12 and 13 may be such that they do not meet atthe point A. In this case only the bottom wall is bonded to the wall 5.Alternatively the top and bottom walls 12 and 13 may meet at the point Abut be of different curvature.

FIG. 4 of the drawings shows a simpler arrangement in which the capsule6 has only the part 7 secured directly to the bottom wall 5 around itsedge 9. When, as shown, the part 7 is secured directly to bottom wall 5,a capsule is formed between the part 7 and the bottom wall 5 inwardly ofthe edge or rim 9. The part 7 includes means for communicating betweenthe interior of the capsule and the exterior thereof. In the preferredembodiment shown, the means is a venting hole 114 in wall 11. Edge 9 maybe curled in on itself.

FIG. 5 shows an arrangement in which a part 8 is bonded to the bottomwall 5 and closed by a laminated foil lid 14.

The arrangement of FIG. 6 is similar to that of FIG. 5 except that thelid 14 is replaced by a dished part 15 having an embossed surface 16.

In all the arrangements above described including FIGS. 1 and 2 it isessential that, for use in beverage cans, no aluminium should be exposedto contact by the contents of the can. Thus while the internal surfacesof the can and the appropriate surfaces of the capsule 6 are coated asdescribed above a problem may arise in venting the capsule 6 to theinterior of the can.

One solution is to form one or more venting apertures through a wall ofthe capsule 6 using a laser drilling technique to ensure the flow-backof protective lacquer into the aperture(s).

Another arrangement is to locate one or more wires radially through theregions while the parts are heat sealed together. After cooling thewires are withdrawn to leave apertures which are internally coated asdescribed above and are not exposed to raw aluminium. The wires may forexample be of stainless steel or they may be coated with "non-stick"material.

FIG. 7 shows an arrangement in which one or more pairs of opposedindents 17 are formed in the rolled edges 9 and 10 and become filledwith adhesive. This body of adhesive is then drilled to provide thenecessary venting aperture(s) without exposing an aluminium surface.

FIG. 8 shows another construction in which plastic rivets such as 18 areinserted through a hole drilled in one or both of the parts 7 and 8. Therivet is sealed with plastics material at its ends so covering aluminiumexposed by the drilling and subsequently a hole is drilled through therivet.

Another potential location of uncoated aluminium is the curled edges 9and 10 of the parts 7 and 8. Conventionally the edge material would beexternally curled back on itself so that a raw aluminium edge wouldoccur only inside the rolled material and within a body of adhesive.FIG. 9 shows an alternative arrangement in which these edges are reversecurled so that during the crimping/sealing operation polypropylenematerial would flow into the rolls to seal the edges from the interiorof the can.

FIG. 10 shows a second chamber 6 of smaller diameter but greater depththan that of FIG. 3. Also in FIG. 10 the parts 7 and 8 are each formedwith a central depression 7a and 8a which meet at a face B so that thesecond chamber is annular in the manner of FIGS. 1 and 2. Here thecentral depressions are also bonded together and the face B may have anaperture (not shown) to ensure that the space C communicates with thebody of the can. The aperture must be appropriately coated.Alternatively the space C may communicate with the body of the canthrough a radial passage (not shown) between the surfaces 5 and 13.

FIG. 11 is another construction in which the parts 7 and 8 arehemi-spherical.

FIGS. 12 to 14 show how the capsule of FIGS. 1 and 2 may be formed witha vent aperture while the two parts 101 and 102 are being bondedtogether. As the parts are brought together in a suitable tool (notshown) with a layer 112 of adhesive between them (or on each part) amandrel 113 is disposed between the rims so that the latter aredistorted around the mandrel. The latter may have a non-stick finish sothat when it is withdrawn a hole 114 coated with adhesive extendsbetween the rims.

In FIG. 12 the mandrel is of constant diameter. In FIG. 13 it has areduced diameter inner end 113a so that the hole 114 is of steppedformation. FIG. 14 is a view in the direction of the arrow A of FIG. 13after withdrawal of the mandrel.

Although it has been assumed in FIGS. 7, 8, 9 and 12 to 14 that theventing of the capsule by providing a hole between the rims should be ina radial direction it will be understood that this hole may extend at anacute angle to a radius so long as it remains in the plane of the rims.It is desirable that in the case of a single hole the ratio between thelength of the hole and the smallest diameter should be between 3:1 and8:1 preferably about 5:1. When multiple holes are used the diameters andratios may be altered.

Instead of using a mandrel as described in connection with FIGS. 12 to14 a wire (preferably tubular to exhaust gases) may be disposed betweenthe rims wholly within the thickness of the adhesive 112. When this wireis withdrawn (to be reused) the appropriate vent hole remains.

Of all the arrangements above described those of FIGS. 1 and 2, FIG. 3or FIG. 10 or FIG. 11 are preferred when the capsule is to be subject tocomparatively high pressure differentials for example during thepasteurisation of cans containing stout and when such cans are opened.However the arrangements of FIGS. 4, 5 and 6 may also be used for thispurpose by locally increasing their wall thickness or, as in FIG. 6, byforming the embossed surface 16.

It will also be understood that the arrangement of FIGS. 4, 5 and 6 mayincorporate the features of FIGS. 7, 8 and 9, insofar as the protectionof raw edges is concerned and the provision of venting means for thecapsule. This has already been referred to in paragraph 5 on page 10hereof.

We wish to emphasize that with reference to the construction of FIG. 4,its edge 9 can be inwardly curled as in FIG. 9 and the raw edge embeddedin protective plastics material.

In general when the capsule is of press-formed aluminium it mayadvantageously incorporate one or more of the following strengtheningfeatures:

1) Convex or concave curvature to one or both of its top and bottomwalls 12 and 13

2) Peripheral flanges such as 9 and 10 to resist hoop stress

3) An embossed (i.e.) ribbed face such as 16 (FIG. 6)

4) Stable location of the capsule against the can base.

5) Thicker materials in some parts of the second chamber. This isparticularly the case in FIGS. 4 and 5.

The arrangements of FIGS. 1, 3, 10 and 11 can be produced having aweight of about 3 gms (as opposed to about 5 gms to 35 gms for aplastics capsule). This reduces the thermal mass of the capsule. A lowthermal mass coupled with the high conductivity of the thin material ofthe capsule assists the pasteurisation process for cans of stout.

Although as described above the container 1 has an inwardly projectingbase providing a lower inner surface it will be understood that acontainer, for example of different material, may have a flat or aconcave inner surface.

In this specification the term "fluid" is to be understood as meaningnot only liquids and gases but also other substances such as pastes,creams and slurries that are flowable at least at selected temperatures.Also, in this specification, we regard aluminum foil as having athickness no greater than 300 um.

Although the present invention has been described with reference topreferred embodiments, workers skilled with art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A fluid container having a generally cylindricalbody and comprising a top, a base and an annular side wall, at leastpart of the body defining a closed primary chamber openable by manuallyoperable means in the top, the base having an upwardly projecting innersurface projecting inwardly of the primary chamber, a member formed ofan aluminum alloy of a thickness no greater than 500 μm having a dishedformation and a rim secured to the inner surface so that the member andthe part of the inner surface inwardly of the rim including an edge andbeing secured to the inner surface so that the member and the part ofthe inner surface inwardly of the rim constitute a secondary chamber andmeans in the member to communicate between the interior of the secondarychamber and the exterior thereof, said edge being coated with aprotective material.
 2. A fluid container according to claim 1 in whichthe member is of aluminum foil of a thickness from 50 to 300 um.
 3. Afluid container according to claim 2 in which the rim has its outer edgeembedded in plastics material and is heat sealed to said inner surface.4. A fluid container according to claim 2 in which the outer edge iscurled upon itself.
 5. A fluid container having a generally cylindricalbody and comprising a top, a base and an annular side wall, at leastpart of the body defining a closed primary chamber openable by manuallyoperable means in the top, the base having an upwardly projecting innersurface projecting inwardly of the primary chamber, a capsule comprisingupper and lower parts, at least one of which has a dished formation andboth of which have a peripheral rim, the rims being secured together sothat the upper and lower parts being distinct from said top, base andside wall and at least partially in register with one another to provideat least one vented secondary chamber extending into the dishedformation, means in at least one of the parts to communicate between theinterior of the secondary chamber and the exterior thereof, and thelower part having its exterior so formed as to enable it to be held instable engagement with the inner surface but so that a fluid may passfreely between those parts of the exterior of the lower part and theinner surface that are not in intimate engagement, said capsule beingdisposed within the container and held in stable engagement against theinner surface.
 6. The container according to claim 5, wherein saidcapsule is toroidal.